Jungle surveyors in Guatemala uncover the breadbasket of the Maya world.

Most of the major Maya sites of the Petén border on bajos, or seasonal wetlands, important resources for the ancient Maya.
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The abandoned city of Yaxhá has everything you might expect at a Maya site: pyramids and stelae, howler monkeys, and a haunting sense of a tragic past. It is located in Guatemala's Petén district, in the heart of the southern Maya lowlands, on the edge of Bajo la Justa, a sprawling 23-square-mile seasonal wetland 18 miles southeast of Tikal. Bajo la Justa is just one of many bajos that make up 40 percent of the Petén landscape. In the rainy season, bajos are swampy thickets, great forested tracts of mud that mire any mule or human foolish enough to set foot in them. But this is May, the last weeks of the dry season, and Tom Sever and Dan Irwin of NASA, and research partners Pat Culbert, professor emeritus at the University of Arizona, and Vilma Fialko of Guatemala's Instituto de Antropología e Historia have been venturing into this vast wasteland every day. They believe that the bajos, once ringed by Maya cities but long ignored by archaeologists, were the breadbasket of the Maya world.

Study the bajos and you'll understand how war may have been just a symptom, how a Maya drought may have been manmade, and why the Maya could not save themselves forever. The team has embarked on a campaign to reconstruct what Culbert calls "an extinct agricultural system," to pull back the jungle's thick green curtain with machetes, pack mules, state-of-the-art satellite imaging, and information gleaned from ceramics, soil cores, NASA computers, and local farming techniques.

They're also working with a sense of urgency, certain that the past holds lessons for today. Stand atop Yaxhá's pyramids and your heart sinks: not 20 miles away, walls of smoke rise in the sky. Settlers are swarming into the Petén, slashing and burning the rain forest, clearing cornfields and cattle pastures. The Mexican lowlands have been almost entirely deforested; the Guatemalan jungle is not far behind.

In a land where 90 percent of the rain falls between May and December, where the porous limestone bedrock sucks away water like a sponge, the Maya made extraordinary efforts to save every drop. Satellite pictures show canal networks and miles of grand causeways that may have been aqueducts. Fialko has found dams and weirs on bajo streams. She has discovered that the floodplain of the Holmul River, once a year-round bajo river linking many of the area's largest cities, is peppered with reservoirs and chultuns, the Maya's bottle-shaped, underground storage pits that may have been dug to catch water.

The team asked Nick Dunning, a University of Cincinnati environmental archaeologist, to take a look at the bajos' soil history. In corings from upland lakes and trenches in dry dirt from several bajos, he found that the Maya's environment underwent a drastic change midway through their tenure. Beginning around A.D. 100, most of the area's surface water disappeared. Several feet below the bajos' surface is a layer of what was once moist, wetland peat, rich with pollen from trees, aquatic plants, and corn; at the end of the Preclassic era, and for the next 500 years, this soil was buried in successive layers of waterborne limestone clay.

These strata tell a story. When paired with the bajos' archaeological evidence, and the findings of other researchers throughout the lowlands, the history of the Maya environment becomes clear. It is a saga of ecological exploitation, change, adaptation, and defeat.

Sever and Irwin use a global positioning system unit to identify sites and vegetation revealed in satellite images. (Tom Gidwitz)
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Adaptation was successful--for a time. The cities grew more crowded, the elite more numerous, the temples and palaces grander still. But by the Late Classic, around A.D. 750, the system's capacity had been reached. Human skeletal remains from the last decades of Maya rule unearthed at the sites of Tikal, Altar de Sacrificios, and Copán suggest a decline in stature and show an increased number of scars from malnourishment. The soil was exhausted, the farming infrastructure weak. Warfare increased. Polities fractured. The end had come.

The Petén landscape is undergoing its greatest transformation since the Maya stripped it bare. In the last 40 years it has lost half its forest as its population has shot from 20,000 to 400,000. As roads slice the jungle open and a quilt of farmland spreads, the soft limestone Maya ruins, stripped of shade, fall prey to heat and rainfall and crumble in the sun. Looters rush in, trash tombs, and buzz-saw sculpture. Many ancient buildings are so perforated with holes they are in danger of collapse.

Says Sever, "We're literally in a race against time."

Tom Gidwitz thanks Tom Sever, Pat Culbert, Dan Irwin, Vilma Fialko, and Liwy Grazioso for their cooperation and hospitality during the preparation of this article.